Dynamic CT of the Adrenal Glands in Normal Dogs

Abstract

Computed tomography (CT) appearance of the adrenal glands has been described dogs with pituitary-dependent hyperadrenocorticism and adrenal neoplasia, and normal dogs. However, to my knowledge, there are no available data on the changes in the contrast-enhancement pattern of the normal canine adrenal glands therefore the contrast enhancement pattern and the attenuation parameters of the normal canine adrenal glands were evaluated, using dynamic CT. Ten healthy beagle dogs were recruited for this study. After survey CT scanning, the dynamic scans (60 scans) were initiated at time of the injection of the contrast medium. The contrast medium with an iodine concentration of 300 mgI/ml was administered with a power injector at a dosage of 640 mgI/kg and a flow rate of 3 ml/s. The time-attenuation curves of the adrenal gland and the aorta were constructed, and based on the changes in the attenuation values, the attenuation parameters were measured. The mean time to adrenal enhancement appearance was 12.3±2.4 seconds after injection, and the mean time to aortic enhancement appearance was 8.55±1.23 seconds after injection. The maximal adrenal enhancement was observed at 21.3±3.15 seconds after injection with a mean attenuation value of 178.9±16.6 HU and the maximal aortic enhancement was observed at 13.95±1.59 seconds after injection with a mean attenuation value of 706.62±140.8 HU. The value for adrenal perfusion by dynamic CT of 2.58±0.67 ml/min/ml is close to the value for adrenal perfusion by fluorescent microspheres. Dynamic CT is an effective method for assessing the changes in contrast enhancement patterns of normal canine adrenal gland and this attenuation parameters will help future evaluation of canine adrenal gland with CT.